Lubricating oil composition containing mixed 2:1alpha- and beta-glycol borate compounds



e A 2,979,459 Patented Ap 11, 1951 LUBRICATING OIL COMPOSITION CONTAINING i yr gr n g zna- AND fi-GLYCOL BORATE CO1 Samuel M. Darling, Lyndhurst, and Chien-Wei Liao,

Cleveland, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Dec. 30, 1957, Ser. No. 705,763

5 Claims. (Cl. 25249.6)

This invention relates to a lubricating oil composition comprising the reaction product of an ot-alkylenediol and 2-methyl-pentanediol-2,4 with boric acid in the ratio of two moles of the diols to one mole of the boric acid.

One of the most serious problems encountered in the operation of internal combustion engines is the deposits which form progressively and accumulate on the surfaces within the combustion zone, on the cylinder head, piston top, sparkplugs and the intake and exhaust valves. These deposits are made more stubborn by the tetraethyl lead present in most gasoline fuels, because this not only contributes to the deposit but it also converts it from an essentially carbonaceous deposit to one comprising appreciable quantities of lead and lead compounds mixed therewith, such as lead sulfate, and lead oxide. The carbonaceous deposits act as a cementing agent for the lead deposits, and the lead deposits are more difficult to remove than the carbon deposits. Thus, a deposit of this sort is more tenacious and troublesome than a purely carbonaceous deposit.-

The nature of the lead-carbonaceous deposits is such that they are quite difiicult to remove, once they have een built up. They are not attacked by the scavenging agents which are included in the fuel with the tetraethyl lead. Despite the fact that the amount of the deposits eventually levels ofi, after which there is no appreciable further increase, the presence of the built-up deposits interferes considerably with the operation of the engine, and it would be desirable both to prevent formation of deposits and to remove them after they have been formed. The disadvantageous efiects of these deposits 'are'well discussed in U.S. Patent No. 2,741,548 to Samuel M. Darling, Philip S. Fay and Lorraine S. Szabo.

It has been proposed to attack such deposits by incorporating in the liquid leaded motor fuel an organic boron compound which is soluble in the fuel. The boron compound is thought to modify the action of the fuel in the engine, and to react with the deposits so that the adverse effects due to the deposits are eliminated or markedly reduced.

It is known that the carbonaceous components of the deposits in the engine are built up not only from the gasoline but also from the oil, which enters the combustion system from the crankcase in various waysf This oil is in the liquid phase in the combustion zone of the engine, whereas the gasoline, of course, is in the vapor phase. However, it is essential that the boron compound be soluble in the medium in which it is introduced into the engine. For use in lubricating oil, the. solubility must be quite high, relative to that in gasoline, because more additive is needed in the lubricating oil to obtain an effect. Moreover, the stability of theh boron compound against hydrolysis must be high, in view of the larger amounts of compound present, and the hydrolysis products must liquid-leaded motor fuels are volatilizable under the combustion zone conditions, and also exist in the vapor phase in the combustion zone. If such organic boron compounds were present in the oil, they would, under the combustion zone conditions, nonetheless be expected to volatilize. Compounds having a much higher boiling point are necessary for use in lubricating oils. Such compounds should also be stable in the presence of moisture. Because of this, it has not been possible to incorporate these compounds in ,the oil.

It has now been determined, in accordance with the invention, that the reaction products of boric acid with mixtures of certain highly branched a-alkylene glycols and 2-methyl-pentanediol-2,4 in the proportion of one mole boric acid to two moles of the mixed aand B- alkylene glycols are oil-soluble, more moisture-stable, and have low volatility, provided the glycol has at least six carbon atoms up to about twenty carbon atoms. Engines operated with lubricating oils containing such boron compounds have improved performance. The deposits are reduced. The ignition temperature of such engine deposits as remain is increased, therefore repressing surface ignition. It is thought that the boron compounds react with the lead in the deposits forming lead borate, and that this does not act catalytically to the same extent because it has a higher flow point than the lead oxide and lead sulfate usually present in such deposits. These additives are compatible with conventional lubricating oil additives.

The reaction products in accordance with the invention are defined by the following general formula:

. 0 I where one of R and R is the ,B-alkylene radical derived from 2-methyl-pentanediol-2,4, i.e., of the structure CH3 CH3 JHC'H2 and the other of R and R is an a-alkylene radical having a straight or branched chain of from six to twenty, preferably from eight to ten, carbon atoms, a chain of two carbon atoms linking the radical to the group, of the following structure:

The free valences are attached to oxygen, as shown in I above. R R R and R are alkyl, and have a sufficient number of carbon atoms in the aggregate to total from four to eighteen carbon atoms. The R R R and R radicals can be straight-chain or branched alkyl radicals; preferably at [least one of R R R and R is branched, preferably tertiary. Thus, R R R and R can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, secondary butyl, amyl, isoamyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl and octadecyl radicals, taken in sufficient number to meet the requirements of the formula for the total number of carbon atoms.

If one a-alkylene glycolis employed, four molecular species are obtainable from the a-alkylene glycol, 2- methyl-pentanediol-2,4 and boric acid, the two borates of each glycol and two mixed borates. The latter will predominate and the Z-methyl-pentanediol-ZA is more (13) CH apt to be in the cyclic structure. Only the mixed borates are represented in the following list, which is typical of CH3- the compounds which come within the invention: i (1) 02115 5 CH3-CHO (5.11, 0211,

0H3-C-0 CH3 on; (14) R B-OK JH-OH'r-(; OH aon, on, CH3- 0 '11, OH, B-OC-OOH 2H CHa-OHO on, on,

(2) 02H: (15) CH3 C2H51-O (3H3 (3H3 CH -O CgHii CH;

B0OH-CHiCOH 15 B-O-(|J-C-OH C2H5?'O CH1 CH3- H-O 02H: OH!

(16) H: E: I

OHaC-O CzHs iso-CuHu 11-04%- -0 CH, CH: I

g p 20 Hi B-OC-- -0H B-O- H-OHz- OH l 5 I CH3- H-O H3 CH: nC4H9- I O CH: (17) CH3 Cm 0H3b--o CH; 011: I1C4H9 l CH2 B-O- -COH XII-C4Hp-C-Q CH3 CH3 i i I 1 OHa-OH-O on; CH=C-CH: B-O-CH-CHr-fiJ-OH 2H: n-C4Hv--CO CH: (18) CH3 OH: cH,-c0 OH; H a on, om A CH & O CH: B-O- --OH CH CH Orn- HO Cg, I a OH: CH: CH B-o-0HcH,( J-0H UHF -CH:

9 CH: CH3

GHCO C Is CH8 It has already been indicated that when one u-glycol is (6) CH3 CH3 CH3 employed, four molecular species are possible. It will be CH l o C H C apparent from the above that more complex mixtures of 2 s 4 reaction products can be obtained from mixtures of three I ..o -C-OH and more a-diols. However, all of these are operative in H3 the compositions of the invention. (7) CH3 CH3 CH8 While any proportions of the a-alkylene glycol and the OH O CH CH 2-methyl-pentanediol-2,4 can be used, it is preferred that rra I at least 25% up to about 75% of each glycol be present. (I111, B--O-CCOH The borate compounds of the invention are solids or CHFCH O Ha CH: liquids which are stable to moisture. The liquids and (8) CH3 the solutions of the compounds in oil remain homogeneous CH j 0 CH C H and clear when stored in a moisture-saturated chamber for 3 2 5 forty-eight hours at room temperature (25 C.). They 0H1 B-0-0-C-OH are soluble in petroleum lubricating oils at very large CHVCEFO H3 2H5 concentrations. They are substantially involatile at crank- (9) OH: case temperatures.

These compounds can be preared by mixing the remark-"O tert CH' actants in the stoichiometric 2:1 molar ratios and heating I Hg B0-C- them above C., up to about 150 C., on a steam plate cm-oH-o H3 3113 or hot plate, WltiTOCCflSlOHEIl stirring, until the theoretical (m) E gInOlfiHt of water is lost. The loss of water is determined y t e weight loss of the reaction vessel and contents CH CO CH -C H 3 ten 4 0 Alternatively, the reactants can be refluxed in the stoichio- H2 BOOH--C-OH metric ratios in dry benzene in a flask provided with a CHPCEPO Ha E water condenser and a water-collecting trap until the (11) CH: theoretical amount of water has been azeotropically dis- CH3- O CH CH tilled. This permits use of a lower temperature. The I a 5 water removed is determined by the water in the trap. OH: BO-C-COH The benzene then is removed from the reaction mixture by CHPCEPO (8235 distillation, and the residue vacuum-distilled or recrystal- 12 GHQ hzed' CH *C V O CH CH, Mixtures including the pairs of compounds numbered 3 I (1) and (l7), (2) and (19), and (3) and (20) abovewere OH: B-0Li 0-0151 sub ected to screening tests to determine oil solubility, E, moisture stability and volatility. Oil solubility was ob- I served at a concentration of about 0.1% boron. Moisture stability was studied with both the undiluted liquid addi- CH3 Cm '15 tive and an oil solution containing at least the equivalent of 0.1% boron. Samples had to remain visually un-' changed with respect to homogeneity and clearness after being stored in a moisture-saturated chamber for fortyeight hours. Volatility was determined by the distillation The borate compounds of the invention can be used with any petroleum hydrocarbon oil of lubricating viscosity. The SAE viscosities for lubricating oils range from No. to No. 70. The neutral oils and refined oils, such as the acid-treated and solvent-extracted oils, are equally useful in the compositions of the invention. The oils may be blended from suitable bright stocks and finished nuetral or refined oils of light and heavy viscosities. It is impossible here to give a complete decription of the various methods used in the preparation of lubricating oils, but reference is made to the text by Georgi entitled Motor Oils and Engine Lubrication, published by Reinhold Publishing Corporation, New York (1950), chapter V, Wherein the various types of lubricating oils are discussed fully. Any of the oils mentioned therein can be employed in the compositions of the invention.

Relatively large amounts of the organic borate compounds of the invention, in oils as compared to the amounts required in gasoline, are neededto give an improvement in engine performance. All proportions of the compounds are based on the amount of boron in the compound as a percent of the total oil composition, since it is the boron that is the active component in removing the deposit. At least 0.05% is the minimum. Use of amounts in excess of 0.5% usually cannot be justified economically, and excessive amounts may lower the viscosity index. v

The composition of the invention is prepared simply by mixing the boron compound with the oil at room temperature. The boron compound is soluble in the oil, and dissolves therein either instantaneously or after a short time. No solvents are required.

The following examples represent in the opinion of the inventors the best embodiments of their invention:

Examples 1 to 3 Three lubricating oil compositions were prepared using a lubricating oil blend of 67% solvent-extracted neutral oil, 300 SSU at 100 F. and 33% of a solvent-extracted bright stock, 78 SSU at 210 F. To the oil was added 2% of the following mixture of borate compounds:

Example 1:

When the above oils were used the crankcase of an internal combustion engine operating for a period offover seventy-two hours on nonboron-containing gasoline and the engine was then dismantled, the deposits in the combustion chamber were found to contain boron with the attendant advantages of the same in the deposit as discussed earlier. a

The compositions were subject to the Falex E. P. test, run by the standard procedure, where the load on the hearing was increased automatically and the pressure reported was that registered at failure. The wear tests were run on the same equipment using a constant. pres-- sure on the bearing.

The data showed that the oil of the invention containing the boron compound tolerated higher pressure and produced less wear than either the corresponding blend without boron or the base oil alone, thereby indicating that there would be no adverse effect by the use in crankcases of engines.

The extraordinary moisture stability of the compounds of .the invention is'explained by postulating the existence of a chelated structure, in which the free OH group is attached to the boron by a semicovalent bond, thus:

where one of R and R' is:

CH: CH; -JJHCH2 and the other is an a-alkylene group having from six to twenty carbon atoms having the structure:

where R is an a-alkylene group having from six to twenty carbon atoms having the structure:

the free valences being attached to oxygen, and R R R and R being alkyl, the amount of said compound based on the Weight of' the lubricating oil being equivalent to from 0.1 toO.5% by weight of boron. v

'3. Petroleum lubricating oil having dissolved therein a moisture-stable organic boron compound having the formula:

and the other is an a-alkylene group having the following structure:

(3211a CzHa HaC(/-(3CHa the amount of said compound based on the weight of the lubricating oil being equivalent to from 0.1 to 0.5 by weight of boron.

4. Petroleum lubricating oil having dissolved therein a moisture stable organic boron compound having the formula:

and the other is an u-alkylene group having the following structure:

the amount of said compound based on the weight of the lubricating oil being equivalent to from 0.1 to 0.5 by weight of boron.

5. Petroleum lubricating oil having dissolved therein a moisture-stable organic boron compound having the formula:

and the other is an a-alkylene group having the following structure:

CH HaC-(il B CH, the amount of said compound based on the weight of the lubricating oil being equivalent to from 0.1 to 0.5% by weight of boron.

References Cited in the file of this patent UNITED STATES PATENTS 2,526,506- Rogers et al. Oct. 17, 1950 2,710,252 Darling June 7, 1955 2,741,548 Darling et a1. Apr. 10, 1956 2,795,548 Thomas et a1 June 11, 1957 2,821,539 Newman et a1. Jan. 28, 1958 FOREIGN PATENTS 722,537 Great Britain Jan. 26, 1955 UNITED STATES PATENT OFFICE CERTIFICATlON OF CQRRECTION Patent No. 2,979,459 April 11, 1961 Samuel M, Darling et al;

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 66, for "theh" read the column 3, lines 44 to 46, the left-hand portion of formula (7) should appear as shown below instead of as in the patent:

CH -C0 same column 3, lines 70 to 72, the right-hand portion of formula (12) should appear as Shown below instead of as in the patent:

l "A l f fifll lain, lll i gml wwmwl mlwfiilll -%OH tart-0 th;

column 4, line 54, for "preared" read prepared column 5, TABLETI, heading to column 1 thereof, for "Glycerols" read Gflycols same column 5, lines 64 to 66, the right-hand portion of the formula should appear as shown below instead of as in the patent:

F -C-OH Signed and sealed this 5th day of September 1961. SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Gcmmissicner of Patents 

1. PETROLEM LUBRICATING OIL HAVING DISSOLVED THEREIN A MOISTURE-STABLE ORGANIC BORON COMPOUND HAVING THE FORMULA: 